Between June and August, 15 percent of smartphone owners said they recently acquired their handset (within the last three months), bringing smartphone penetration up to 64 percent of mobile phone owners in the U.S. And among recent acquirers, 80 percent percent chose smartphones as their mobile handset.

So who owns smartphones now, and where are the opportunities for growth? Young adults aged 25-34 have the highest smartphone penetration at 81 percent, and teens aged 13-17 are catching up, as nearly 70 percent of this group now uses smartphones. Mobile users over the age of 55 remain the minority of smartphone owners. In fact, 50 percent of the mobile subscribers using feature phones in the U.S. were those aged 55+, highlighting significant room for smartphone growth among this group of mobile users.

Overall in the U.S. smartphone market, Android remained the leading mobile operating system, with 53 percent of smartphone owners running Android handsets, while Apple remained the largest smartphone manufacturer (40% of smartphone owners).

Among recent acquirers, more than nine out of 10 purchased either an Android or Apple device, with 61 percent of consumers choosing Android handsets and 34 percent picking iPhones.